Use of naphtha reflux



Nov. 6, 1951 USE 0F NAPHTHA REFLUX Filed June 22, 1948 @une 6m vs/v r zo* F29. l. L

. INVENTOR. ST5/H511 EFI'eE-EMAN BVS@ gifs@ HT Toe/VEY.

s. E. FREEMAN l 2,573,898

Patented Nov. 6, 1951 UNITED .STATES PATENT QFFICE USE oF NAPHTHA nEFLUX Stephen E. Freeman, Pittsburgh, Pa., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., .a corporation of. Pennsylvania Application J une 22, 1948, Serial No. 34,453

(Cl. Z130-428.5)

obtained by solvent fractionation is separated.

A second object is to reduce the viscosity of the oil-solvent mixture undergoing extraction.

A third object is to improve the output ofthe l.apparatus employed in effecting the fractionation.

A fourth object is to obtain a fraction of glyceride oil of exceptionally high iodine value in vwhich the formation of polymers of oil or solvent and other phenomena is reduced to a minimum.

A fth object of the invention is to obtain oils of improved iodine value as above described in a highly economical manner.

A sixth object of the invention is to obtain'a fraction of a glyceride oil which is of exceptionally high iodine value but is low in color, free'fatty acids and other impurities.

' A seventh object of the invention is to obtain more saturated fraction of glyceride oil, low in color and free fatty acids and which is more desirable for `conversion into good products than the original oil.

These and otherobjects ofthe invention will 4be 'apparent from consideration of the following s peciication and the drawings.

`In the drawings, Figs. 1 and 2 are diagrams or H'iiow sheets illustrating two slightly different Ytonseed o il and others include as their main constituent glycerides of higher fatty acids notably saturated acids on the one' hand such as palmitic acid, and stearic acid and unsaturated acid on the other hand such as oleic acid, linoleic acid, y

linolenic acid and others in minor proportions.

`It is understood that the'acid radicals tend to assume uniform distribution in the glyceride molecules, that is, most of the molecules will comprise a mixture of two or more of the fatty acids. However, some of the glyceride molecules doV actually possess a higher degree of unsaturation than the others.

In accordance with mypriorPatents 2,200,391 and 2,200,390 and my copending applicationsr Selas furfural.

rial No. 335,005 of May 13, 1940, now abandoned, and Serial No. 705,807 of October 25, 1946, now

abandoned, of which the present application is a vcontinuation-impart, it is found that the glycerides yof higher degree of unsaturation can be successfully separated from those of higher degree of saturation by contacting the glyceride oils 'in liquid phase with certain polar solvents such In this manner it is possible to separate from many of the oils and notably the drying or semi-drying oils such as soybean oil, considerable amounts of glycerides of highly unsaturated character well adapted for use in the formulation of paints and varnish which are adapted toV airY dry, or in the production of air-drying alkyd'resins whichare then further adapted for use in the coating industry.

In order further to improve the iodine value of the extracted oil so obtained, it has been proposed to refluxy or recycle a part of the extract oil after extraction and partial or complete removal of the furfural, to the lower Zones of the extraction column. This refluxing results in important improvements in theV iodine value of the extracted pil. However, it is found that by application of such technique there is also a tendency to build up ythe concentration of coloring matter, vantioxidants and other objectionable constituents in theextrac't'. This tendency is particularly pronounced if small extract yields are to be taken.

'The 'present invention contemplates an improvement upon the simple technique involved in merely contacting the oil witha selective polar solvent and then separating the resultant phases and evaporating offthe solvents to obtain the more saturated and less saturated components of the oilsas separate fractions.v More specifically the invention resides, as one step, in the employment of naphtha as a reflux which is added to the lower portions of the extraction zone containing oil and furfural in a counterfcurrent column, in such amount and under such conditions that the iodine value of the extracted oil obtained `fromthe lower portion of thecolumn is greatly improved, there being a substantially sharper separation of the more unsaturated glycerides from the more saturated glycerides. As a second step, the invention comprises backwashing the extract solution of glyceride oil containing ley-products suchv as naturalcoloring matter, sterols, free fatty acids, tocopherol and other anti-oxidants, etc.

with naptha to remove nearly all of the glycerides, but leaving the byfproducts, then recovering the glyceridesv from the naphtha as a reiined. high iodine fraction. By application of this technique, a high iodine value extract product is obtained and at the same time, there is substantially less tendency to carry back into the extraction system coloring matter and other byproducts Which are objectionable in the extract product.

In the practice of the invention, a glyceride oil such as soybean oil, linseed oil, cottenseed oil, corn oil, sardine oil, peanut oil or the like, that contains glycerides, at least some of which contain one or more fatty acid radicals which are olefinically unsaturated and preferably some of which are dior even tri-olefinically unsaturated along with by-products as mentioned, is subjected to counter-current extraction with a polar solvent such as furfural in a column. Simultaneously, a reflux of naphtha is introduced near the bottom of the extraction zone. This reflux is usually small. about .1 to .5 the volume of feed oil, but in those cases where the ratio of polar solvent such as furfural to oil is high, the volume of reflux may be increased in the manner illustrated in certain of the subsequent examples. A polar solvent (furfural) solution of the more highly unsaturated components of the oil, is taken off at the bottom of the system and a solution of more highly saturatedl or completely saturated oils containing most of the naphtha is taken off at the top of the extraction zone.

As a feature of the invention, the extract solution of glyceride oil and by-product is re-extracted with a larger volume of petroleum naphtha than that used as reflux, to take out the fraction of more unsaturated glycerides. The petroleum naphtha employed may be any hydrocarbon or mixture of hydrocarbons which is immiscible or but partially miscible with furfural, but preferably is one of relatively high boiling range, e. g. 290 to 370 F., and having a Kauri Butanal Value in the'range of 36 to 39. Other naphthas of either higher or lower boiling range are contemplated, 'and these may include any hydrocarbon which is liquid at the temperature of operationV and is not unduly high in boiling range, and which is immiscible or but partially miscible with furfural or other polar solvent employed. This range may include, for example, hexanes and other hydrocarbons through the range of kerosenes. The petroleum naphtha is employed in substantially higher ratio in column I6 than is employed as a reflux in column I6. A good average ratio of naphtha to original feed oil, in column I6, would be about 1 to 3 parts per part of feed oil, e. g. as disclosed in one of the subsequent examples, 2.4 to 1. However, if the proportion of furfural is high, in the extract, the proportion of naphtha feed in column I may be increased correspondingly. Obviously, it should not be so increased as to strip out all or substantially all of the free fatty acids.

It is also to be observed that the temperature of column I6 is substantially lower than that of column I0. This differential may be 10 to 60 F., e. g. about 40 or 50 F. The differential of optimum operation will vary for different oils and different ratios of solvents. Lower temperatures in the backwash column I6, favor clean and thorough separation of the glycerides from the furfural phase, since the solubility of the oil in furfural drops rapidly with drop of temperature, while the temperature at least within reasonable limits, does not substantially change the miscibility of the glycerides and naphtha.

There is no particular lower limit of temperature for the backwashing of the furfural solution, except those of economics and the point at which glycerides tend to crystallize out.

The naphtha and residual furfural in the naphtha solution can be distilled olf to obtain the extract product.

One convenient embodiment of apparatus useful for the practice of the invention is illustrated by the flow diagram in Fig. 1. In accordance with the procedure illustrated in this diagram, glyceride oil such as soybean oil, linseed oil or cottonseed oil, corn oil, peanut oil, sardine oil or the like, is introduced at Il into an intermediate portion, for example, in a zone somewhere between the upper and lower fourths of the column I0. Polar solvent such as furfural is introduced into the upper part of the column at a point I2. Preferably sufcient space is left above the point of introduction of the polar solvent, to permit the raffinate solution containing naphtha in the clearing section Iii-a, top of the column, adequately to separate from the solvent Vmedium before the-raffinate phase is drawn olf as indicated at I3, say 5 or 10 feet above the point of inlet of furfural, in order to permit the phases to separate before the raffinate is drawn off. All or a part of the space IIJ-c, between inlets l2 and I4, may be filled with a packing such as Berl saddles, Raschig rings or the like, designed to effect thorough contact of the liquids in the column. The packing may be supported at its bottom by perforated plates and additional plates at appropriate intervals.

Non-polar solvent, such as naphtha, which is of lower densityY than the polar solvent, is introduced near the bottom of the column and at at point substantially below the point of introduction of the oil, for example, at least 10 and preferably 30 or 40 feet below the inlet for the oil. Much more space is permissible. The upper limit is imposed by economics. There should also be a space, Iii-b, say 5 or 10 feet or more, at the bottom of the column below the point of introduction of the naphtha, for purposes of permitting the solution of oil and polar solvent adequately to separate from the naphtha before the solution is withdrawn from the bottom of the column, as indicated at I5. An excess of clearing space at the top or bottom, for phase separation, is permissible. A phase interface will usually form at some level between lines I2 and I II.

The furfural solution of high iodine value oil from column IG, may be subjected immediately to distillation to remove furfural, but the solutions preferably are passed to a second packed column I6 for extraction with an excess of naphtha introduced at Il (1 to 5 volumes based on oil feed) to remove all except an amount equivalent to 0.3% to 1.5% of the original oil and to leave in solution most of the free fatty acids, tocopherols, sterols, chlorophyll and other coloring matter. A. clearing section IS-a, say 2 to 10 feet or mora-may be left above inlet I5.

Naphtha containing an extract of the more highly unsaturated glycerides, passes off at I8. Furfural, containing the by-products, passes off at I 9 from bottom clearing section I6-b. A phase interface will usually form at some point between inlets I5 and II. The solvent from the extract and ranate solutions may be removed by distillation.

In the operation of a system in accordance with the provisions of the present invention, it is :ramasse desirable that the volume of I pola'rI solventlibe maintainedas low as practicable, consistent with f extraction column ina lowerproportonwith respect to the furfural feed, in a proportion of e. g. .1 to 1.5 volumes with respect tothe volume of oil. lIf very large volumes of 'furfural are employede. g. 10 vto 20 volumes per volumevof oil,

the ratio of naphtha maybe considerably higher, even up to or above 2 to 5.

The temperature of the system is adjusted in such manner that the proportion of oil in the extract from thebottom of the column falls within the limits of 10 to '70% of the total oil. This temperature, of course, will vary with different cils, different solvents yand different solvent ratios. For soybean oil, it preferably will be within a range of about 90 to 125 F. Usually the temperature for a given oil at a given solvent ratio, can be determined by heating oil and solvent in desired ratio, to miscibility temperature. Operating temperature forcolumns l or 21 will usually be to 60 F. lower than this miscibility temperature. The temperaturevmay be attained by preheating the glyceride oils or the solvent media before theyare introduced into the-column, or by the provision of appropriate cooling or heating coils or jackets in conjunction-with the column. The application of such devices does not constitute a specific element'of `the present invention. The temperature may be controlled by heat exchanger 20, supplied with an appropriate medium through linesZU-a. f

The rainate of more highly saturated glycerides drawn off at I3', will be of lower iodine value than the feed oil. Assuming that the initial oil is soybean oil, one of the best for purposes'of the present invention, the iodine value'will be approximately 110 to 130, dependent upon the feed oil and the manner in which the column is operated. For example, at a givensolvent ratio assuming that a large volume of raffinate is desired,

Athe column will beoperated comparatively cool, .thus assuring that the furfural dissolves a low proportion of the oil. 4The oil .which is dissolved by the furfural or polar solvent, however, will and-presencefof objectional natural pigments,

crude or degummed oils must be alkali refined :and bleached for the removal of these objectonal constituents before the oil may be processed 'into food products such as salad oils or hydrogenated products.

In the above process where degummed soya oil is used as the feed oil, the major portion of the free fatty acid and certain objectional pigments. notably the chlorophyll, are removed with the extract fraction, leaving a railinate relatively free` of fatty acid and chlorophyll. The break vconstituents concentrated in this fraction may berel moved bylight alkali refining, water 'degurnming or other conventional methods. The ranate oil produced by this process is' thereforexrenedin yrespectto free fatty acid and chlorophyll .and may be processed intofood Vproducts .in a more simple and economic manner.

then be of maximum iodine value. If a large extract of moderate iodine valueisdesired, the temperatureV can be raised. However, if the temperature `is increased to such a degree that the phases within the column become completely miscible, the system becomes inoperative and fractionation impossible.

The raflnates from the column, as drawn out through the line I3, should beV appropriately treated in order to eliminate the solvents therefrom. For example, the solvents may be evaporated under vacuum, or steam distilled. The specie technique of distillation is not regarded as being an essential feature of the present invention.

An important feature of the invention resides in the fact that the raffinate or more saturated `Yglyceride oil fraction is refined in theprocess.

'gummed--oils such as degummedsoya oil. Normally, because of therelatively'highacid-value Typical data illustrating percentage chlorophyll reduction of a raffinate treated as above described, are as follows:

original oil Lffuole The chlorophyll content of the low iodine value fractions is about one tenth that of the original Y oil. These rafnates of low chlorophyll content -can be readily processed to white shortening.

The furfural extract solution from lcolumn i0 as obtained from line I5, may be subjected to further naphtha extraction in order to strip out most of theglycerides, leaving in the furfural solution only about 0.3-2.0% of the glycerides, along with large proportion of the free fatty acids, coloring matter, sterols and the like. For this purpose,the extract solution from line i5 'is passed to the upper extremity of column I6,

- in addition to the high iodinev value glycerides,

xfree fatty acids, chlorophyll, other natural pigments. and unsaponiiiable matter. By means of naphtha extracting'this solution in column I6, a naphtha extract of glyceride oil of improved color and free fatty acid content is obtained. This high iodine value fraction is a break free, varnishgrade oil, even though the feed oil may have been a crude or degummed oil.

The by-product solution removed at i9 contains the major portion of the free fatty acids land chlorophyll in addition to other natural pigments, a concentration of the unsaponifiable matterand Vtraces of break constituents.

In a run in the apparatus shown in Figli,

-soybean oil which had been rened to remove breakandbeing of an iodinevalue of 132.2, was

tfurfural extracted. The conditions Aof `:the `run were: f v.

Oil feed, 30 parts Furfural (dry), 660 parts, saturated with naphtha at 135 F.

Naphtha reux, 68 parts (Parts are by volume.)

The column Ill was at 135 F. The glyoerides in the extract solution could be stripped out with naphtha in column I6. An extract product in a yield of 62% of 150 I. V. was recovered. A 38% i `yield of raiiinate iodine value 104, was obtained.

The extract was a good drying oil.V The rafnate Was a good oil and could easily be hydrogenated to provide a solid fat.

In a further example, soybean oil, iodine value 135.9, was extracted With urfural in column l0. Column temperature. at topf108.5.toV 110 F.; at the bottom 111.5 to 112 F. The feed rates in parts by volume were:

Soya oil 30 Furfural 90 Naphtha reux 6 The extract oil could be recovered with naphtha in column I6, at a temperature of 60-80 F.

manner with furfural in column l0. The temperature is at an optimum at about 118 F. but may be 5 to 10 degrees higher or lower. A -furfural feed of 3 to 8 parts by volume, e. g. 3 parts based on the feed oil may be employed. YA reux of .1 to 5 parts by volume of naphtha based on the feed oil may be introduced at H.

The glycerides could be extracted out of the furfural in column I6 using naphtha. The optimum temperature is about 70 to '15 F. The proportion of naphtha based on the feed oil rate may be about 1 to 1.

Linseed oil can also be treated in the same way. The temperature of the column l for 1inseed oil may be about 80 F.

In a further example, break Ifree, or refined soybean oil, iodine value 138 was extracted in column I0.

The column temperature was90-91 F.

The ratios of the feeds to the column in parts by volume were:

Furfural 200 Feed oil 40 Naphtha reflux at bottom of column l2 In column I6, the temperature was maintained within a range of 50 to 80 F.

Results Extract Railnate Weight Yield, per cent Iodine value Oil and .Fat Products.V1 A. E. Bailey, Interscience Publishers, 194:5',v` page 501.` Column Ill was at a. temperature of 112.5 F. at the top and 115V F. at the bottom. Column I6 was at a temperature of 70 F.

Proportions in parts by volume:

Furfural Oil 15 Naphtha reilux at I4 5 Naphtha backwash at Il 2'1 Practically all of the glycerides could ,Y be extracted out of the furfural phase by application of naphtha in column I6, at a temperature about 40 F. below that in column l0.

Results By-Prod- Extract Railinate uct Per Cent Yield.- 31. 8 67. 5 0.7 Iodine va1ue 155. 8 123. 0 Color good good black Per Cent Free Fatty Acid 0.036 0. 061

The following constitute specic constructions and operational data for a. commercial operation, using the invention as illustrated in Fig. 1:

A. Primary column 10 Total height, 84 ft., 8 in.

Packed height, 66 ft., 3 in.

Clearing sections a. Top, 3 it., 6 in.

b. Bottom, 8 ft., 3 in.

4. Diameter of column, 22 in.

. Feed positions (height from bottom of column) a. Furfural, ft., 10` in. b. Oil, 32 ft., 8 in. c. Naphtha reux, 7 ft., 10 in.

6. Phaseinterface position-from 23 ft., 5 in.

to 30 ft., 5 in. from bottom of column.

'7. Condition of operation column l0.

3. Clearing sections a. Top, 3 ft., 0 in. b. Bottom, 3 ft., 0 in. Diameter of column, 15 in. 5. Feed positions (height from bottom of column) a. Extract solution, 43 ft. b. Naphtha, 3 ft.

6. Packing used, 1 in. Raschig rings 7. Interface position-from 38 ft. to 43 ft. from bottomof the column. Y

bl. Temperatures (-1) Top of column, 64 to 78 F. (2) Bottom of column, 58 to 65 F. Y Y(3) Extract solution, 65 to 80 F. v (4) Naphtha, '58 to 65 F.

n C. Quality of feed oils used Y The oils used in these runs were degummedsoya oil whose constants fell within the following ranges: Iodine Value, 129.3 to 131.3 Per cent free fatty acid, 028-0199 Color.l (Gardner), 91/2 to 101/2 P-er cent chlorophyll, .000m-.60034. Perv cent carotene, .D04-.0668

. D. Quality of products produced Extract Rafiinate By'lgod'- recourtYield... 26e-srs cie-72.5 0.7-1.3 Iodine value inl-153.0 12M-126.3 137.9 Percent free fatty acid. 0.2-0.8 Y .O4-.O75 16.2 Per cent tocopherol 2. Per centrrunsaponlxable matter 7.89

A second apparatus of slighty-different character is indicated diagrammaticllay in Fig. 2. This apparatus 'comprises two columns which may be conveniently arranged with respect to each other; The first column 2| is provided near its upper extremity, with an inlet 22 for polar solvent such as furfural, and it is provided near its lower extremity with an inlet 23 for the glyceride oil to be treated. The inlets 22'and 23 are spaced from the extreme ends of the column a sufcient amount to admit of the proper solution separation before thesolutions are withdrawn, e. g'. 5 to 15 feet. The raflinate passes out at the top of the column as indicated at 26, the exact is drawn off at thebottorn as indicated` at26. The extract comprising a fraction of oil ofnincreased unsaturation, may be withdrawnA and passed to the upper extremity of a second column 21, constituting a reflux zone. The feed and iiow is appropriately maintained andcontrolled by the Valve indicated diagrammatically at 29.

A reflux of naphtha is introduced near the lower extremity of column 2i, through a line 36. The furfural solution or polar solvent extract containing most of the free fatty acids, sterols and highly unsaturated glycerides, is drawn off at the bottom of the column, as indicated at 3|. The naphtha extract containing some `of the glycerides initially withdrawn in the furfural solution, passes from the top of the column as indicated at 32. This solution is returned to the bottom of `the column 2| at a point somewhat ,above the bottom thereof, so that the glycerides associated therewith, are returned to the column 2| and subjected to further fractionation. The raiiinate solution passes out of column 2| at 24|, and the solvent may be removed from the oil by distillation. l'

The furfural glyceride oil-by-product mixture from line 3l may be discharged into the uppery part of a third column 33, where nearly all of the glycerides, e. g. of those present in the extract solution, are extracted out by an upwardly iiowing current of naphtha introduced at 32 near Ythe bottom of the column. `Highly unsaturated extract oil dissolved in naphtha, is drawn off at 36 at-the topy of thecolumn. Byproduct and a minor amountof glyoerides are drawn at 31 near the bottom of the column, The solvents may be evaporated or ysteam stripped from the fractions obtained at 36 and 31. v

It is to be understood that all of the columns It, I6, 2|i 21 and 33 as herein disclosed, may be effecting intimate and uniform contact with` polar solvent, naphtha and oil, without channeling or separation into streams. That is, the phases should permeate throug'n eachother, probably as fine dropletsv but without such emulsication as would prevent phase separation and would eliminate the phase interface. Before orafter the evaporation of the solvent, the resultant glycerides of relatively highly unsaturated nature, may be subjected to any desired technique such as further bleachingA or treatment, toremove any residual anti-oxidants which may be retained and concentrated therein as a result oi the various extraction operations to which the oil is subjected. 1

In a specific example, soybean oil containing chlorophyll and other naturally occurring pigments, free fatty acids, sterols, etc., was fed in at `therinlet of the column 2| shown in Fig. 2 through line 23, in a proportion of 25 parts by volume. The column 2| was maintained at 111 F. The furfural was introduced through line 22 l in a proportion of parts by volume. i

-Furfuralextract solution containing'oilof increased iodine value was taken off at 26 and passed to the column 21 slightly below thev upper extremity thereof. Column 21 Was also maintained atabout 111 F. A reflux of naphtha comprising aliphatic hydrocarbons averaging about 9 carbon' atoms and free of or nearly free of aromatics, was introduced into the system as in'- dicated at 30 in a proportion of 10 parts by volume. `A raffinate solution containing moderately saturatedr glycerides was Withdrawn at 32 from the column 21 in a proportion of 15 parts by volume. and was then returned to the column f 2|' and-subjected to further fractionation. The extract solution from column 21'could'be back- Washed with naphthain column 33.

The glyceride oil was initially of an iodine value of approximately 130. This value, of course, will vary somewhat with the source of the oil and the particular season in which it is produced. Usually it will be to 135.

As a result of the treatment above described, there was obtained an extract oil passing out in solution with the furfural at 3| from the column 21. This extract constituted 33.8% of the total oil and had an iodine value of 146.4. The raflinate passing out at 24 from column 2| constituted 66.2% and had an iodine value of 121.2.

Cottonseed oil could be substituted for soybean oil in the foregoing examples. A temperature of 118 F. in column I6 would'be at or near the optimum, 70 F. in column I6 could likewise be employed. A reux ratio of .1 to .5 based upon oil input iscontemplated.

Similarly linseed oil could be substituted. The

column l may be at 80 F. A reux of .1 to .5 could be employed.

With either cottonseed oil or linseed oil, the ratios of oil to furfural may be those previously specified for soybean oil.

The forms of the invention described are'to be regarded as being byway of example only. It will be apparent to those skilled in the art that numerous modications may be made therein without departure from the spirit of the invention or the scope of the'appended claims.

I claim:

1. A process oi obtaining a fraction of glyceride oil of high iodine value, good color and relatively low free fatty acid content, from an oil of low iodine value containing` substantial amounts of the foregoing impurities, which method comprises the steps of counter-currently flowing the oil to furfural by introducing fur'fural into an upper part of an elongated extraction zone,A and oil into the same extraction zone at a point below the point of introduction of furfural, then further introducing a reux of naphtha at a point below that of introduction of the oil in an amount and at a temperature to obtain a furfural extract solution comprising to 70% of the oil, withdrawing the furfural extract solution at the bottom of the extraction zone, then further ex tracting at least 95% of the'glycerides of the oil from the furfural extract solution with naphtha,

in a second extraction zone and evaporating the naphtha to recover the fraction.

2. -A process of obtaining a fraction of aglyceride oil of high iodine value, good color and relatively low free fatty acid content from a low iodinevalue oil and containing coloring matter and free fatty acidsfwhich method comprises countercurrently extracting the oil with three to eight volumes of furfural per volume of oil, in an elongated extraction zone in which the furural is introduced near the top, and the oil at a point below the point of introduction of the furfural, and .1 to 1.0 volumes of naphtha is intrdouced at reux at a point below the introduction of the oil, whereby to obtain a furfural extract solution constituting. 10 to '70% of the original oil of oil high in iodine value and by-r products, withdrawing said extract solution from the extraction zone at a point near the bottom thereof, and extracting the glycerides from the furfuralsolution by counter-currently flowing the solution against naphtha in a second zone, the naphtha being in a proportion of 2 to 5 volumes per volume of original oil and evaporating the naphtha to recover the fraction.

3. A process as def-ined in claim 1 in which the oil treated is soybean oil.

4. A process as dei-ined in claim 2, in which the temperature of the second zone is l0 to 60 F. lower than that of the first.

5. A process as dened inV claim 1, in which the oil treated is degummed soybean oil.

6. A process as deiined in claim 2, in which the oil treated is degummed soybean oil. A

l7. In a process of obtaining Va fraction of soybean oil of high iodine value, good color and low fatty acid content from a low iodine value soybean oil containing coloring matter and free fatty acids, the steps which comprise introducing the oil into the middle portion of an extraction zone, introducing furfural at the top of the zone and naphtha as a reiux at the bottom of the zone, the furfural being in a proportion of` 3 to 8 volumes per volume of oil, the naphtha as reflux being in a proportion of .1 to 1.5 volumes per' volume of oil, the extraction zone being main' tained at a temperature of 90 to 120 F., withdrawing at the top of the extraction zone naphtha and ranate oil of low iodine value, withdrawing at the bottom of the extractionrzone an extract solution of oil of high iodine value, free fatty acids and coloring matter in furfural, then pass-v ing the extract solution to the top of a second extraction zone and introducing naphtha at the I bottom of said zone, the ratio of naphtha beingV from' 1 to 5 volumes per volumeY of original oil, the temperature of the second extraction zone being within a range of to 80 F. whereby to obtain a naphtha solution of the glycerides of low free fatty acid content and coloringcontent and to leave in solution in the furfural not more than .3 to 1.5% of the original oil, then evaporating the naphtha solution to obtain said fraction.

STEPHEN E. FREEMAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date l 2,278,309 Freeman Mar. 31, 1942 2,355,605 Ruthrui et al Aug. 15, 1944 OTHER REFERENCES Ruthruff et al., American Institute of Chemical Engineers Transaction Section A, vol. 37, 1941, pages 649-667.

Bailey, Ind. Oil and Fat Products, 1945, Interscience Pub. Co., pages 655-657. 

1. A PROCESS OF OBTAINING A FRACTION OF GLYCERIDE OIL OF HIGH IODINE VALUE, GOOD COLOR AND RELATIVELY LOW FREE FATTY ACID CONTENT, FROM AN OIL OF LOW IODINE VALUE CONTAINING SUBSTANTIAL AMOUNTS OF THE FOREGOING IMPURITIES, WHICH METHOD COMPRISES THE STEPS OF COUNTER-CURRENTLY FLOWING THE OIL TO FURFURAL BY INTRODUCING FURFURAL INTO AN UPPER PART OF AN ELONGATED EXTRACTION ZONE, AND OIL INTO THE SAME EXTRACTION ZONE AT A POINT BELOW THE POINT OF INTRODUCTION OF FURFURAL, THEN FURTHER INTRODUCING A REFLUX OF NAPHTHA AT A POINT BELOW THAT OF INTRODUCTION OF THE OIL IN AN AMOUNT AND AT A TEMPERATURE TO OBTAIN A FURFURAL EXTRACT SOLUTION COMPRISING 10 TO 70% OF THE OIL, WITHDRAWING THE FURFURAL EXTRACT SOLUTION AT THE BOTTOM OF THE EXTRACTION ZONE, THEN FURTHER EXTRACTING AT LEAST 95% OF THE GLYCERIDES OF THE OIL FROM THE FURFURAL EXTRACT SOLUTION WITH NAPHTHAIN A SECOND EXTRACTION ZONE AND EVAPORATING THE NAPHTHA TO RECOVER THE FRACTION. 